feat: opt-in scored related posts and category neighbours
- golem15.journal.related_mode (category | scored, default category) and
golem15.journal.related_count (3 to 6, default 3, clamped) in
config/config.yaml; classes.ReadRelatedSettings reads them
- the default mode answers GET /posts/{slug} exactly as before
- scored: related posts ranked by 2 points per shared tag plus 1 per
shared category, ties by newest, in one scoring query
(classes.ScoredRelatedPosts), published only for visitors; the answer
adds previous_in_category and next_in_category, the neighbours by
publish time within the post's first category by name
(classes.CategoryNeighbour), in the direction of previous_post and
next_post
- TestRelatedDefaultUnchanged, TestRelatedScored (a draft and a future
post sharing every tag never shown) and TestRelatedScoredCountClamped
This commit is contained in:
Jakub Zych
176
classes/related.go
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176
classes/related.go
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package classes
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import (
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"context"
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"strings"
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"time"
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"git.golem15.com/golem15/sm-journal-plugin/models"
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"git.golem15.com/golem15/summercms/modules/compass"
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"gorm.io/gorm"
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)
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// Related posts and category neighbours of a post (D-82, P33-44). Opt-in:
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// golem15.journal.related_mode is "category" by default, which keeps the
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// post answer as it has always been (posts sharing a category, three,
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// newest first). "scored" ranks the related posts by shared tags and shared
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// categories and adds the neighbours within the post's first category.
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const (
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// RelatedModeKey is the config key of the related-posts mode.
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RelatedModeKey = "golem15.journal.related_mode"
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// RelatedCountKey is the config key of the number of scored related
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// posts, clamped to RelatedCountMin..RelatedCountMax.
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RelatedCountKey = "golem15.journal.related_count"
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// RelatedModeCategory is the default: today's related posts.
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RelatedModeCategory = "category"
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// RelatedModeScored ranks by shared tags and categories.
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RelatedModeScored = "scored"
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RelatedCountDefault = 3
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RelatedCountMin = 3
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RelatedCountMax = 6
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// Points per shared tag and per shared category.
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relatedTagPoints = 2
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relatedCategoryPoints = 1
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)
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// RelatedSettings is the related-posts configuration.
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type RelatedSettings struct {
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// Mode is RelatedModeCategory or RelatedModeScored.
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Mode string
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// Count is the number of scored related posts (3 to 6).
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Count int
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}
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// Scored reports whether the scored mode is on.
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func (s RelatedSettings) Scored() bool { return s.Mode == RelatedModeScored }
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// ReadRelatedSettings reads golem15.journal.related_mode (anything but
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// "scored" is the category mode) and golem15.journal.related_count (unset
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// or not a number: 3; otherwise clamped to 3..6).
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func ReadRelatedSettings(cfg *compass.Config) RelatedSettings {
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out := RelatedSettings{Mode: RelatedModeCategory, Count: RelatedCountDefault}
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if cfg == nil {
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return out
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}
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if strings.EqualFold(strings.TrimSpace(cfg.String(RelatedModeKey)), RelatedModeScored) {
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out.Mode = RelatedModeScored
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}
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if n := cfg.Int(RelatedCountKey); n > 0 {
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out.Count = min(RelatedCountMax, max(RelatedCountMin, n))
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}
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return out
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}
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// publishedClause is the visitor rule of the public API (applyPublished in
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// controllers/api): published, with a publish time in the past.
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const publishedClause = "p.published = ? AND p.published_at IS NOT NULL AND p.published_at < ?"
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// ScoredRelatedPosts is the scored mode's related posts of post: other posts
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// sharing a tag or a category, ranked by 2 points per shared tag plus 1
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// point per shared category, ties by the newest publish time (then the
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// higher id), at most count. Posts that share nothing are never related.
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// Visitors see published posts only; editors (includeDrafts) also see
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// drafts, as the category mode's related posts do. One query computes the
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// scores; the rows come back with their author, categories and tags.
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func ScoredRelatedPosts(ctx context.Context, db *gorm.DB, post *models.Post, count int, includeDrafts bool) ([]models.Post, error) {
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if post == nil || count <= 0 {
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return []models.Post{}, nil
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}
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db = db.WithContext(ctx)
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q := db.Table("golem15_journal_posts AS p").
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Select("p.id, ? * COALESCE(st.n, 0) + ? * COALESCE(sc.n, 0) AS score", relatedTagPoints, relatedCategoryPoints).
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Joins(`LEFT JOIN (SELECT post_id, COUNT(*) AS n FROM golem15_journal_posts_tags
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WHERE tag_id IN (SELECT tag_id FROM golem15_journal_posts_tags WHERE post_id = ?)
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GROUP BY post_id) st ON st.post_id = p.id`, post.ID).
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Joins(`LEFT JOIN (SELECT post_id, COUNT(*) AS n FROM golem15_journal_posts_categories
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WHERE category_id IN (SELECT category_id FROM golem15_journal_posts_categories WHERE post_id = ?)
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GROUP BY post_id) sc ON sc.post_id = p.id`, post.ID).
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Where("p.id <> ?", post.ID).
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Where("(st.n > 0 OR sc.n > 0)")
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if !includeDrafts {
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q = q.Where(publishedClause, true, time.Now())
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}
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var ranked []struct {
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ID uint
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Score int
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}
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if err := q.Order("score DESC, p.published_at DESC NULLS LAST, p.id DESC").Limit(count).Scan(&ranked).Error; err != nil {
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return nil, err
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}
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if len(ranked) == 0 {
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return []models.Post{}, nil
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}
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ids := make([]uint, 0, len(ranked))
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for _, r := range ranked {
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ids = append(ids, r.ID)
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}
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var rows []models.Post
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if err := db.Model(&models.Post{}).Preload("User").Preload("Categories").Preload("Tags").
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Where("id IN ?", ids).Find(&rows).Error; err != nil {
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return nil, err
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}
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byID := make(map[uint]models.Post, len(rows))
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for _, r := range rows {
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byID[r.ID] = r
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}
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out := make([]models.Post, 0, len(ids))
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for _, id := range ids {
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if r, ok := byID[id]; ok {
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out = append(out, r)
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}
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}
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return out, nil
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}
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// PrimaryCategoryID is the post's first category by name, ties by id (the
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// order the :category URL param takes its category in); 0 without one.
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func PrimaryCategoryID(ctx context.Context, db *gorm.DB, postID uint) uint {
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var rows []struct{ ID uint }
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err := db.WithContext(ctx).Table("golem15_journal_categories AS c").
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Select("c.id").
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Joins("JOIN golem15_journal_posts_categories AS pc ON pc.category_id = c.id").
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Where("pc.post_id = ?", postID).
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Order("c.name ASC, c.id ASC").
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Limit(1).
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Scan(&rows).Error
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if err != nil || len(rows) == 0 {
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return 0
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}
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return rows[0].ID
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}
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// CategoryNeighbour is the post's neighbour by publish time within its
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// first category, in the direction of the post answer's previous_post and
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// next_post: previous is the nearest published post published after it,
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// next the nearest one published before it (ties by id). nil without a
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// category or a neighbour. Published posts only, as for previous_post.
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func CategoryNeighbour(ctx context.Context, db *gorm.DB, post *models.Post, previous bool) *models.Post {
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if post == nil {
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return nil
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}
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category := PrimaryCategoryID(ctx, db, post.ID)
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if category == 0 {
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return nil
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}
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op, dir := "<", "DESC"
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if previous {
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op, dir = ">", "ASC"
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}
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// The same query shape as the site-wide neighbours (siblingPost), plus
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// the category, so the row is read the same way.
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q := db.WithContext(ctx).Model(&models.Post{}).
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Where("published = ? AND published_at IS NOT NULL AND published_at < ?", true, time.Now()).
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Where("id <> ?", post.ID).
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Where("id IN (SELECT post_id FROM golem15_journal_posts_categories WHERE category_id = ?)", category)
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if post.PublishedAt != nil {
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q = q.Where("(published_at "+op+" ?) OR (published_at = ? AND id "+op+" ?)", post.PublishedAt, post.PublishedAt, post.ID)
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}
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var out models.Post
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if err := q.Order("published_at " + dir + ", id " + dir).Take(&out).Error; err != nil {
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return nil
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}
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return &out
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}
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